Examplary embodiments relate to semiconductor memory devices, and more particularly to methods of reading data in nonvolatile memory devices and methods of operating the nonvolatile memory devices.
Semiconductor memory devices can be generally divided into two categories, according to whether they retain stored data when disconnected from power. These categories include volatile memory devices, which lose stored data when disconnected from power, and nonvolatile memory devices, which retain stored data when disconnected from power. Memory cells of a nonvolatile memory device, such as a flash memory device, may be classified into single-level memory cells (SLCs) that store one bit of data per memory cell and multi-level memory cells (MLCs) that store more than one bit of data per memory cell. MLCs may have different patterns of threshold voltage distributions depending on the number of bits of data programmed in the MLCs. Typically, a nonvolatile memory device including MLCs may include at least one flag cell that represents the number of bits of data programmed in corresponding MLCs.